Sharper Asymptotically Optimal CDC Schemes via Combinatorial Designs
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Coded distributed computing (CDC) was introduced to greatly reduce the communication load for MapReduce computing systems. Such a system has K nodes, N input files, and Q Reduce functions. Each input file is mapped by r nodes and each Reduce function is computed by s nodes. The architecture must allow for coding techniques that achieve the maximum multicast gain. Some CDC schemes that achieve optimal communication load have been proposed before. The parameters N and Q in those schemes, however, grow too fast with respect to K to be of great practical value. To improve the situation, researchers have come up with some asymptotically optimal cascaded CDC schemes with s+r=K from symmetric designs. In this paper, we propose new asymptotically optimal cascaded CDC schemes. Akin to known schemes, ours have r+s=K and make use of symmetric designs as construction tools. Unlike previous schemes, ours have much smaller communication loads, given the same set of parameters K, r, N, and Q. We also expand the construction tools to include almost difference sets. Using them, we have managed to construct a new asymptotically optimal cascaded CDC scheme.
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